Patent GB-462456-A (GB)
Title: Manufacture of cellulose derivatives and of artificial filaments, films and other shaped structures therefrom
IPC: C08B11/00
Filed: 1935-05-29
Abstract: Alkali-soluble cellulose ethers obtained by treating alkali cellulose with alkylating or hydroxyalkylating agents or with halogen fatty acids, are prepared under such conditions that the relationship between the caustic alkali, water and cellulose in the alkali cellulose is within the following limits per one C6H10O5 unit: (1) caustic alkali not substantially exceeding 0,4 mols., water not less than 5 mols. and not more than 20 mols.; (2) caustic alkali 0,4--1,0 mol., water not less than 15 mols.; (3) caustic alkali not more than 0,2 mols., water not less than 25 mols. per one mol. of caustic alkali; (4) caustic alkali not more than 0,2 mols., water less than 1,5 mols. down to no water.  By the use of these proportions of caustic alkali and water, ethers are obtained which can be readily washed, and furthermore there is no substantial loss of caustic alkali; in addition they permit the use of caustic alkali solutions of less than 8 per cent strength, for example, of 5 per cent strength, in the preparation of the alkali cellulose, and of pressing the alkali cellulose to give a mass containing very small amounts of caustic alkali solution, and of the use of reduced amounts of etherifying agents.  Mixed ethers may be obtained by treatment of the alkali cellulose either p  simultaneously or successively in either order with different etherifying agents.  The etherification may be carried out at room temperature or below room temperature or at a raised temperature, and in the presence of diluents and catalysts; and the treatment of the cellulose with alkali and etherifying agent may be carried out simultaneously or successively in either order. The product of the etherification after if desired suitable washing and purification is worked up by solution in caustic alkali solution if necessary with lowering of the temperature as described in Specification 212,864, [Class 2 (ii)]; and the solution is worked up into filaments and other shaped structures with the aid of coagulating baths capable of coagulating viscose, in particular with baths having a coagulating and plasticizing effect such as 25--70 per cent sulphuric acid, or in a succession of baths, the first having a coagulating effect and the second being capable of plasticizing the coagulated material.  The cellulose ethers may, however, be converted into other cellulose derivatives such as nitrates, phosphates, formates, acetates, propionates, benzoates, sulphonated derivatives, nitriles and cyanogen and cyanuric derivatives; they may also be worked up as by the processes described in Specifications 12854/12, 6035/13, 149,320 and 177,809, [all in Class 2 (ii)], into cellulose ethers which are soluble in water or in organic solvents. Technically important are the products obtained by xanthating the cellulose ethers soluble in caustic alkali by acting upon these in solution or in the moist state with carbon bisulphide in the presence of caustic alkali; after treatment with carbon disulphide, the resulting xanthates may be purified or isolated before solution in caustic alkali solution in preparation for working up into filaments, films and other shaped structures, for which uses they may be used alone or in admixture with other colloids such as cellulose xanthates, the latter being prepared, for instance, simultaneously with the cellulose ether xanthate by reacting with carbon bisulphide on a mixture of cellulose ether and cellulose.  Any suitable softening agents may be added to the xanthate solution. The Specification contains a number of examples illustrating the manufacture of the cellulose ethers, the working-up of these into filaments, films and fibres with or without stretching during the coagulation, as coatings on woven fabrics, as printing compositions, as adhesive layers for paper, cardboard or fabrics, and into thick plates; and other examples illustrating the further conversion of the cellulose ethers into cellulose ether xanthates, and the working-up of solutions of these into filaments, fibres, coatings, impregnations, dressings and sizes, for printing, and for the manufacture of thick plates and the preparation of adhesive layers, and for such uses there are used coagulating or coagulating and plasticizing baths, such as are referred to above in connection with the working-up of the cellulose ethers.  The following Specifications also are referred to: 25246/11, [Class 2 (iii)]; 177,810, 200,816, 200,834, 203,346, 203,347, 216,475, 217,166, 231,807, 231,808, 231,809, 231,810, 231,811, 281,352, 312,197, 323,731, 323,732, 335,906, [all in Class 2 (ii)]; 341,843, 341,899, 341,930, 357,121, 357,154, 357,526, 357,549, 374,964, 385,979, 390,517, 390,518, 393,932, 408,932, and 408,950.